No, you only need to create one account.
You can create an unlimited number of payers and recipients on the Manage Payers and Manage Recipients pages on the site. These pages are found under Payers & Recipients on the navigation bar. Once a payer or recipient is created, the contact information is stored in your account.
When filing a form, simply select the payer and recipient from the drop-down selection boxes on the form. All contact information will be filled in on the form.